The present invention relates to a process for treating a yarn and/or a fabric to form a fine inorganic particulate material in the intra-yarn pores and/or on the surfaces of the fibres constituting the yarn or fabric, which would substantially maintain fabric reflectance after repeated wash/wear cycles without affecting the desired characteristics of air permeability. The invention also relates to a treatment product composition directed to provide instant inorganic deposits in the yarn or fibre surface.
It is well known that yarns used for producing fabrics and the fabrics so obtained have pores. In particular, the yarns per se, have inter-fibre pores while the fabric obtained of such yarn apart from such inter-fibre/intra-yarn pores also have inter-yarn pores. It is found that during use of the fabric, particulate soils and/or oily soils get trapped in the minute intra-yarn pores which get firmly bonded to the yarn or fabric.
In a typical hand washing cleaning operation using a detergent solution, the yarn or fabric has the detergent applied to it or it is soaked in the solution which is then followed by rubbing with a brush to dislodge and remove soil and particles from the soiled fabric. By the action of rubbing with a hard surface in presence of a conventional detergent product the cleaning is generally satisfactory. Machine wash is another method used for cleaning fabric where the mechanical agitation in presence of a detergent composition is used to dislodge the soil particles to achieve necessary cleaning.
An unsoiled new fabric generally has a reflectance value of about 88 when measured at a wavelength of 460 nm with UV filter. It is found that following soiling and wash regimes, fabric reflectance may drop to below 65 leading to greying of the fabric. It is established that smaller dirt/soil particles pose a serious challenge in terms of their removal since they accumulate in intra-yarn pores and on the fibre surface. Such small soil particles deposited in or on the fabric are the main cause for decline in fabric reflectance.
U.S. Pat. No. 4,035,148 (Procter and Gamble), U.S. Pat. No. 4,566,980 (Creative Products) and U.S. Pat. No. 4,873,000 (Sterling Drug) disclose carpet treatment products which involve particulate material deposits in the carpet fibres. The particles are subsequently vacuumed off together with any dirt or soil to which they are associated. All the available art uses xe2x80x9cexternal depositionxe2x80x9d techniques i.e. particulates were taken in bulk solution and deposited onto the fabric and then removed.
WO 9842909 (Koala Konnections) discloses a fabric with UV blocking particles bound to the fabric by binding agents. It discloses the process of deposition followed by heat treatment.
In the pending application GB 9929838.2 (Unilever) fine particles of clay are deposited on the fabric which block the inter-fibre regions of the fabric thus preventing the entrapment of environmental soil into the fabric. In order to maintain the reflectance of the fabric it needs to be retreated for deposition of fresh sacrificial layer after each wash and wear cycle. Although this provides satisfactory cleaning, the deposit of the clay on the fabric blocks the inter-fibre and inter-yarn regions which lead to substantial reduction in air flow passage through the fabric adding to the discomfort of the wearer of the fabric.
The present inventors have surprisingly found that a fabric or yarn which comprises fine particulate inorganic particles either on the surface or in the pores of the fibres maintains the fabric reflectance after repeated wash/wear cycles without affecting the desired characteristics of air permeability.
According to a first aspect, the present invention provides a process for the production of a treated textile yarn or fabric which comprises treating the yarn or fabric with at least two reagents capable of reacting together to form a fine inorganic particulate material, whereby the fine inorganic particulate material is precipitated in the intra-yarn pores and/or on the surfaces of the fibres constituting the yarn or fabric.
According to a second aspect, the invention provides a treatment product comprising at least two separate ingredients capable of reacting together in an aqueous medium to form a fine inorganic particulate material, preferably having a particle size not exceeding 5 xcexcm.
The Process For the Production of a Treated Textile Yarn or Fabric
In this first aspect of the invention, the fine inorganic particulate material in the intra-yarn pores and/or on the fibre surface can be provided by reacting in an aqueous medium a first reagent selected from mineral and organic acids and a second reagent selected from alkali or alkaline earth metal salts with inorganic anions.
The mineral acid may be selected from hydrochloric acid, sulphuric acid, nitric acid or phosphoric acid. If hydrochloric acid is used it is preferably at a concentration of from 0.1 to 0.8 gmol/l. If phosphoric acid is used it is preferably at a concentration of from 0.02 to 0.2 gmol/l.
The inorganic anion may be selected from silicate, aluminate, carbonate, hydroxide, phosphate, chloride, sulphate or nitrate and preferably aluminate or silicate.
In a first preferred embodiment, the process of producing the treated fabric/yarn comprises:
(a) treating the yarn or fabric with one of the first and second reagents in aqueous solution,
(b) subsequently, treating the yarn or fabric with the other of the first and second reagents in aqueous solution
to facilitate deposition of the inorganic particulate in the intra-yarn pores and/or fibre surface.
Preferably in the above process, in step (a) the yarn or fabric is treated with the reagent solution having the lower diffusion coefficient. This is to prevent the first reagent from coming out of the intra yarn pores when the second reagent is added to the yarn or fabric. The second reagent with higher diffusion coefficient penetrates into the intra yarn pores and reacts with the first reagent which is already present there.
In a second preferred embodiment, the process of producing the treated fabric or yarn comprises treating the fabric or yarn with an aqueous solution of alkali metal silicate and urea whereby silica is precipitated in the intra-yarn pores and/or on the surfaces of the fibres constituting the yarn or fabric.
In a third preferred embodiment such a process comprises treating the yarn or fabric with a dilute alkali metal silicate solution, through which CO2 is bubbled, whereby silica is precipitated in the intra-yarn pores and/or on the surfaces of the fibres constituting the yarn or fabric.
Alternatively, the process of producing the treated fabric/yarn comprises treating the yarn or fabric with a dilute alkali metal silicate solution followed by drying the yarn or fabric in air, whereby silica is precipitated in the intra-yarn pores and/or on the surfaces of the fibres constituting the yarn or fabric.
Preferably the drying is carried out for a period of at least two hours such that complete conversion of the alkali metal silicate into silica is achieved. The deposition of silica is dependent upon the concentration of the alkali metal silicate solution as well as the drying time and the deposition can be varied depending upon the desired end deposit on the yarn/fabrics.
It is found that yarn or fabric treated by the above process has deposits of fine inorganic particulate material providing for reduced soiling of fabrics, including oily soils, and maintaining higher reflectance in repeated wear/wash cycles.
It is believed that the yarn or fabric treated by the above process has selective deposition of the particulate material only in the small intra-yarn pores and not in the inter-yarn regions which provides firstly, the maintenance of fabric reflectance even after repeated wash/wearing cycles is achieved and secondly, the desired air permeability through the fabric pores is maintained to provide comfort in use or wearing of the fabric.
The Treatment Product
The second aspect of the present invention is a treatment product which comprises at least two separate ingredients capable of reacting together in an aqueous medium to form a fine inorganic particulate material, preferably having a particle size not exceeding 5 xcexcm. It is preferred that the product comprises (a) at least one first ingredient selected from mineral and organic acids and (b) at least one second ingredient selected from alkali or alkaline earth metal salts with inorganic anions wherein (a) and (b) are capable of reaction in an aqueous medium to form a fine inorganic particulate material.
The product is preferably accompanied with an instruction manual detailing directions of use of the product for carrying out in-situ deposition of the inorganic particulate material in the intra-yarn pores and/or on the surfaces of the fibres constituting the yarn or fabric.
The constituent (a) of the product is preferably a mineral acid, preferably selected from, hydrochloric acid, sulphuric acid, nitric acid and phosphoric acid. Alternatively it is also preferred that (a) is an organic acid, preferably selected from citric acid, acetic acid and lauric acid or a combination thereof.
The constituent (b) of the product is selected to have an inorganic anion selected from alkali metal silicate, aluminate, carbonate, hydroxide, phosphate, chloride, sulphate or nitrate and preferably aluminate or alkali metal silicate.
In a first preferred embodiment of the invention, ingredient (a) comprises hydrochloric acid in a concentration of from 0.1 to 0.8 gmol/l and (b) comprises sodium aluminate in a concentration of from 0.1 gmol/l to 0.8 gmol/l.
In a second preferred embodiment of the invention, ingredient (a) comprises phosphoric acid in amount of 0.02 gmol/l to 0.2 gmol/l and (b) comprises sodium aluminate in a concentration of 0.1 gmol/l to 1.0 gmol/l.
In a third preferred embodiment of the invention, ingredient (a) comprises a mineral acid selected from hydrochloric acid in a concentration of from 0.1 to 0.8 gmol/l and phosphoric acid in a concentration of from 0.02 to 0.2 gmol/l and (b) comprises alkaline earth metal salt selected from sodium aluminate and sodium silicate in a concentration of from 0.04 gmol/l to 0.4 gmol/l.
The invention is further illustrated by the following non-limiting Examples.